Deal is controversial because of sweeping security crackdown that has detained one million Muslims

A Hong Kong-listed security firm run by Erik Prince has signed a deal with authorities in China to build a training centre in Xinjiang, where Uighur Muslims have experienced a huge security crackdown.

Frontier Services Group, which specialises in providing security and logistics for businesses operating in risky regions, said it had signed a deal to run a training base in the city of Kashgar, according to a statement posted on its Chinese website.